Dental bur cooling device



June 21, 1966 J. v. BORDEN 3,256,604

DENTAL BUR COOLING DEVICE Filed May 14. 1959 3 Sheets-Sheet 1 FEE- INVENTOR JOHN M BORDEN ATTORNEY June 21, 1966 J. v. BORDEN 3,256,604

DENTAL BUR COOLING DEVICE Filed May 14, 1959 5 Sheets-Sheet 2 INVENTOR JOHN M BURDEN ATTORNEYS June 1966 J. v. BORDEN DENTAL BUR COOLING DEVICE 5 Sheets-Sheet 3 Filed May 14, 1959 8| INVENTOR JOHN M BORDE N WZ M ATTORNEYS United States Patent 3,256,604 DENTAL BUR COOLING DEVICE John V. Borden, Ransom, W. Va. Filed May 14, 1959, Ser. No. 813,092 23 Claims. (Cl. 32-28) This application is a continuation-in-part of my copending application Serial No. 679,552, filed August 22, 1957 which is in turn a continuation-impart of application Serial No. 634,860, filed January 18, 1957, now abandoned.

This invention relates to a dental drill and specifically to high-speed air-driven drills having means to place a coolant on the area being drilled.

An important object of this invention is in the provision of bur cooling means for a high-speed dental drill arranged completely below the rotating mechanism so as not 'to increase the diameter of the housing and diminish the operators view of the drilling area.

A further object of this invention is to provide a handpiece having an air-driven turbine with a water supply which, when mixed with portions of the exhausted air, will form a spray in the vicinity of the drilling bur. This spray will aid in lubricating and cooling the area of the tooth whch is being drilled.

A further object of this invention is to provide a dental handpiece with a circular or semi-circular annular water recess compartment which lies below the rotating elements associated with the dental bur and so arranged that a coolant is delivered downwardly in a direction approximately parallel to the axis of the bur.

A still further object of this invention is to provide novel mixing chambers for the air and water so that they will form a mist in the vicinity of the dental bur.

Another object of this invention is to provide a circular or semi-circular annular water groove which is easily formed within the handpiece and which will be so positioned as to constantly cool the lower portion of the rotor housing. In one embodiment of the invention this groove is formed on the exterior bottom surface of the handpiece, and in another the groove is positioned in a similar position, but is enclosed or consists of a piece of tubing.

The extreme speeds presently used to cut tooth materials have created special cooling problems in the prevention of damage to the nerve tissues inside the tooth, and in the prevention of pain from the generated heat. The heat damage and pain come not so much from the increased speed itself, but result from the inability of maintaining a coolant on the rapidly rotating bur because of increased centrifugal force of the bur throwing away any cooling jet coming from only one direction, especially when that direction is approximately transverse to the axis of the bur shaft. The deepest point in the cavity being drilled is oftentimes that area which requires the coolant the most. This invention provides the coolant to reach those areas by ejecting the water along axes parallel to the bur shaft.

This heating problem could also be solved by forcing large quantities of water into the tooth from several directions, but this results in a fan of water thrown out by the bur which will splash the dentists eyes and face, and also flood the mouth of the patient, causing gagging and other discomfortures.

Accordingly, another principal objective of this invention is to create adequate cooling by directing water or air alone, or air-water mixtures from a plurality of points substantially directly above and circumscribing the drilling bur area. This plurality of sources achieves cooling with a volume of coolant well within the capacity of the usual suction devices found on a dental unit.

A further objective of this invention is in the provision of a washer bearing which provides a seat for the rotating Patented June 21, 1966 mechanisms and in addition provides fluid direction channels for the coolants involved. This washer, with only a minor structural change, can direct the coolants in a variety of ways.

One other objective of this invention is to provide coolant delivery means on the outside of the handpiece utilizing the principle of osmosis.

Further objectives and advantages of this invention will be apparent from the following description and claims wherein the construction, arrangement and cooperation of the several parts of the spray-producing mechanism are set forth.

In the drawings:

FIG. 1 is a cross-sectional view of a lower part of a dental handpiece showing a particular spray-producing means;

FIG. 2 is a bottom view of the handpiece shown in FIG. 1;

FIG. 3 is a cross-sectional view of another type mixing arrangement;

FIG. 4 is a view along the line ll-*4- of FIG. 3;

FIG. 5 is a bottom view of a handpiece having a semicircular water chamber;

FIG. 6 is a cross-sectional view of another form of this invention;

FIG. 7 is a View along the line 77 of FIG. 6;

FIG. 8 is a sectional view along the line 8-8 of FIG. 9;

FIG. 9 is a bottom view of a handpiece having an external water delivering recess; and

FIG. 10 is a cross-sectional view of a handpiece having its recesses covered.

Referring now to FIG. 1, the lower portion of a dental handpiece is designated by the numeral 10. The upper portion of this handpiece is designed in a way known to the art 'and is eliminated here for the purpose of simplicity and clarity. The handpiece is comprised generally of the cylindrical housing 12 and the handle 14. The cylindrical housing 12 is of a conventional type having an open top and a screw-fitted cap. The housing is tapered at its lower end at 11. The elements of the rotating mechanism are inserted through the top of the housing. The housing has a substantially flat retaining bottom 16 having a centrally disposed bur-receiving opening 18. The bottom 16 also has a plurality of water apertures 20 and air apertures 22 circularly arranged in pairs. Circumscribing and spaced from the bur opening 18 on the interior' side of bottom 16 is an annular recess 24. This recess is covered by the resilient washer 25, which may be inserted through the top of the casing 12, to form the annular recess compartment 27. The recess may be machined into the interior bottom surface, and the Washer 25 is held in place by the outer race of the lower ball bearing 30.. Another washer like 25 will be placed between the upper ball bearing and the housing, but will not have any recess-forming function. Each of the Washers may be formed of plastic or metal.

Each pair of apertures 20 and 22 terminate in a series of mixing chambers 23, which chambers are spaced about the lower surface of bottom 16, below and substantially in line with the recess 24.

The bur 26 is detachably secured to the rotating mechanisms with-in the housing 12 by means of a plastic sleeve 17 which is secured to the rotor 32. The means for detachably securing the bur to the rotating mechanisms is of any type known to the art, and forms no part of this invention. Mounting the rotating mechanisms to th housing are ball bearings 30.

The air for rotating the turbine 32 is directed through structures taught by FIGURES l-4.

vicinity of the turbine through the raceway 31 in lower bearing 30. At high speeds, this air has considerable pressure and forms a compressed skin tight film about the balls of the bearing. In this invention the air which is thus expended from the vicinity of the balls is utilized by directing it through a plurality of air apertures 22 which lead to the exterior mixing chambers 23.

A water supply means 36 is directed through the handle 14 into the lower portion of housing 12. As best seen in FIG. 1, the water supply means 36 consists of a conventional water inlet tube 38 carrying water through handle 14 to th annular recess compartment 27.

The mixing chambers 23 are of such a design that the air expended from apertures 22 and the water expended from aperture will come in contact and form a spray in chambers 23 which will be directed by the sloping sides 29 to the vicinity of the head 13 of the bur 12.

A further advantageous Way of directing the *air and water to mixing chambers 23 is shown by the structure of FIGS. 3 and 4. In this embodiment the air apertures 22 and the chambers 23 remain substantially the same, but the means for leading the water from annular recess 27' is changed to an annular outlet means 20' which surrounds the aperture 22. Although in production, this structure will be somewhat more expensive, the arrangement provides a water spray of excellent quality.

As best seen in FIG. 3, the annular recess 27 is formed in th resilient washer rather than in the housing itself. This feature results in a production saving and could, of course, be used just as readily with the structure of FIG. 1. The water delivery means (not shown) is raised in this instance to communicate with the recess.

FIG. 5 shows a bottom view of an embodiment incorporating the advantages of this invention having a semicircular water recess. The water recess is designated by the number 57 and may be formed in either the interior surface ofbottom 50, or the downwardly disposed side of the resilient washer bearing previously described. Air apertures 52 lead from the ball bearing area, and water apertures 50 lead from the water recess. The mixing chamber 53 is the same as those previously described. The semi-circular recess allows a spray to be directed against the bur from a plurality of directions and yet provides a dental handpiece of a very uncomplicated production design.

The design and construction of the lower bearing washer is of importance and lends versatility to this invention. FIGURES 6 and 7 are views showing a washer, and illustrate how a washer of this type cooperates within the combination. The washer 60 is comprised of a first annular base element 62 and a vertically extending flange 64 extending from the outer periphery thereof. The elements 62 and 64 provide a seat for the outer race of the lower ball bearing. Formed along the bottom surface of base element 62 is the annular recess 63. As best seen in FIGURE 7 there is a recess 68 in communication with recess 63 for receiving the water inlet tube 76. The operation and structure of this embodiment is thus far the same as that of the structure of FIGURES 1-4; however, it should be noted that the bottom of the handpiece does not have orifices and chambers the equivalent of 20, 22 and 23 described above. In this instance, additional inwardly directed channels 72 are formed in the bottom of the washer to direct water to the space 74 between the housing and the bur sleeve.

Along the lower end of shaft 73 is a flange 76 having an exterior taper 75. This flange reinforces the lower end of the shaft where it is most required, and also cooperates with the taper 77 of the bur shaft opening to form the annular space 74.

In operation, the air and water will come in contact with the rotating flange 76 and subsequently follow the bur shaft to the area being drilled.

The washer 69 may also be used with the handpiece In that event a spray will be formed in the mixing chambers and in addition, a mixture of air and water will travel to bur shaft receiving opening 18 to the bur.

The water-delivering means do not necessarily have to be enclosed within a chamber in the handpiece. Referring to FIGS. 8 and 9, it has been discovered that by forming an annular groove along the bottom of the turbine housing and joining that groove with another groove or grooves such as those shown at 81 and 82, water delivered from a point 83 will be retained in grooves 80, 81 and 82. These grooves are so dimensioned that the water will be held within the grooves 'by capillarity. Exhaust air apertures 78 spaced along the groove 80 and in communication with the interior of the cylindrical housing will continually blow water from groove 80 to the vicinity of the drilling bur. A continuous spray is thereby formed, because water in the groove will continually be attempting to cover the apertures 78. The water-delivering point 83 may be the end of a water-delivery tube within the handpiece handle.

As seen in FIG. 10, one may obtain greater control of the coolant by covering grooves 80, 81 and 82 by a member such as 90, shown in FIG. 10. These members will have slanted openings 78' disposed opposite the apertures 78, for permitting the air to spray water on the drilling bur. However, in another form of the invention, the handpiece can be so constructed that there will be no air apertures, such as 78, in communication with the water groove 80. In this instance the water will leave groove 80 through openings 83 and travel downwardly to the vicinity of the drilling area. 7

Referring again to FIGS. 8 and 9, instead of grooves 80, S1 and 82, a pair of enclosed water tubes could lead water from outlet 83 directly to orifices 78. This also would provide greater control of the water and still permit the air and water to travel toward the bur head in a substantially vertical direction.

In each of the above embodiments there is shown several numbers of mixing chambers and pairs of air and water orifices. The numbers, of course, are optional and this disclosure is not meant to be limited to any particular nature.

It should be noted that in each of the disclosed embodiments the mixing structure is below the rotating elements. This permits the housing 12 to have the bottom taper 11 which in turn permits an operator of the handpiece to have an unrestricted line of sight to the drilling bur, and further allows the coolant to reach the vital points in the drilling area.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto, as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

I claim:

1. In a dental handpiece, a housing having a bur-receiving opening therein, said housing having an interior recess circumscribing saidbur-receiving opening, a plurality of exterior spray chambers disposed exteriorly of said recess, each of said chambers having an aperture in communication with said recess, the interior of said housing having an aperture in communication with said chambers whereby water in said recess, and air in said housing, if pressurized, will mix in said chambers.

2. In a dental handpiece, a cylindrical housing having a centrally disposed bur-receiving opening therein, said housing having an interior recess circumscribing said burreceiving opening, a plurality of exterior spray chambers disposed exteriorly of said recess, each of said chambers having an aperture in communication with said recess, the interior of said housing having an orifice in communication with said spray chambers, said spray chambers having side walls slanted toward an axis through and normal to the plane of said bur-receiving opening, whereby water in said recess and air in said housing, if pressurized, will mix in said chamber forming a spray which will be directed to a plurality of points around a drilling bur.

3. In a dental handpiece, a cylindrical housing having a bur-receiving opening therein, said housing having an interior groove circumscribing said bur-receiving opening, a plurality of exterior spray chambers disposed opposite said groove and having sides slanted toward an axis through the center of and normal to the plane of said bur-receiving opening, each of said chambers having an aperture in communication with said groove, the interior of said housing having an aperture in communication with said spray chambers, each of said two associated apertures directed to a point of juncture in said chambers, whereby Water in said groove and air in said housing if pressurized, will mix in said chambers.

i. In a dental handpiece of the type having an airdriven turbine driving a bur at high speeds, a cooling and lubricating improvement comprising a housing having an annular recess therein, means to deliver water under pressure to said recess, means to transmit a portion of the air used to drive said turbine to points exterior of said housing, and means to transmit water from said annular recessto said points whereby said air and water will form a spray at said points of juncture.

5. The handpiece of claim 4 wherein said housing has a plurality of mixing chambers on its exterior surface and said points of juncture fall within said chambers.

6. In a dental handpiece of the type having an airdriven turbine driving a What high speeds, a bur cooling and lubricating improvement comprising a housing having an annular recess therein, means to deliver water under pressure to said recess, means to transmit a portion of the air used to drive said turbine to points exterior of said housing, and means to transmit water from said annular recess to said points, said handpiece having shaped mixing chambers circularly disposed thereon about said bur and said points falling within said chambers whereby the mixture of water and air in said chambers may be directed against all portions of the drilling bur.

7. A dental turbine housing having an upper end and a bur-receiving end, and an air-driven turbine within said housing between said ends, in combination with bearing means mounting said turbine for rotation within said housing, said housing being provided with inlet means for motive air for driving the turbine and also provided with inlet means for coolant liquid, means for transmitting water from said inlet means to a plurality of points near said bur-receiving end of said housing, and air delivery means positioned to direct air exhausted from said turbine to combine with Water at said points, whereby a spray of mixed air and water will be formed at said points of union.

8. The housing described in claim 7 wherein said hearing means includes an annular washer between the interior surface of said bur-receiving end and said turbine.

ii. The housing described in said claim 8 wherein said washer has a recess therein which comprises a portion of said water-transmitting means.

it A dental handpiece comprising in combination, an air driven turbine, a housing for receiving said turbine, a handle connected to said housing and having means to direct air to said turbine, the bottom wall of said housing having a centrally disposed bur-receiving opening therein, upper and lower bearing means for supporting said turbine, means forming an annular recess between said bottom wall and said lower bearing means, means for directing water under pressure to said annular recess, said bottom wall having a plurality of mixing chambers circularly disposed about its exterior surface and having pairs of orifices leading from each of said chambers, the first orifice of each of said pairs communicating with said annular recess and the second orifice of each of said pairs communicating with the interior of said housing whereby in operation, said pressurized water, and air expended from the vicinity of said turbine, will meet in said chambers and form a spray.

11. The handpiece defined in claim 10 wherein said upper and lower bearing means are resilient.

12. The handpiece defined in claim 10 wherein said chambers have side walls slanted toward an axis normal to the plane of said bur-receiving opening.

13. The handpiece defined in claim 10 wherein said means forming an annular recess is a groove in said lower bearing means. 7

14. The handpiece defined in claim 10 wherein said means forming an annular recess is a groove in said bottom wall of said housing.

15. In a dental handpiece of the type having an airdriven turbine driving a bur at hi h speeds, a cooling and lubricating improvement comprising a housing having a top end and a bur-receiving end, said housing having a groove along the exterior surface of said bur-receiving end, and an aperture in communication with said groove and the interior of said housing, and means to deliver .water to said groove whereby air expended from said turbine exhausts air through said aperture which forces water from said groove.

16. A dental handpiece comprising in combination, an air-driven turbine, a housing containing said turbine, a handle connected to said housing and having means to direct air to said turbine, the bottom wall of said housing having. a centrally disposed bur-receiving opening therein, upper and lower bearing means supporting said turbine, means forming an annular recess between said bottom wall and said lower bearing means, means for directing water under pressure to said annular recess, means for directing water from said recess to said bur-receiving opening and means to direct air exhausted from said turbine to said bur-receiving opening. i

17. The handpiece described in claim 16 wherein said water-directing means includes a plurality of grooves formed in said lower bearing means.

18. A dental drill, comprising in combination, a housing, a gas-driven turbine therein, a handle connected to said housing, said handle being provided with separate inlet means for gas and liquid coolant and having means to conduct gas from the inlet means to the turbine, said housing at one end thereof having an opening through which a bur-shaft may extend, liquid coolant delivery means comprising an annular conduit between said turbine and said opening, means to conduct liquid from said liquid coolant inlet means to said conduit, said conduit being enclosed by said housing and surrounding said opening, means to direct coolant from said conduit against said drilling bur, and means to conduct a portion of the gas discharged from the turbine into intimate contact with said coolant liquid to form a spray prior to contact with the drilling bur.

19. In a dental handpiece of the type having an aird-riven turbine driving a bur at high speeds, a cooling improvement comprising in combination, a turbine housing having a bur-receiving opening at one end thereof, a bur holding sleeve attached to said turbine, a reinforcing flange having an exterior taper at one end of said sleeve, and means to direct a coolant against said taper whereby said coolant will be directed toward said bur.

20. The handpiece described in claim 19 wherein said bur-receiving opening has a taper of approximately the same slope as said flange taper to aid in directing said coolant.

21. A dental turbine housing having an upper end and an oppositely disposed bur-receiving end provided with a central opening, and an air-driven turbine within said housing between said ends, in combination with bearing means mounting said turbine for rotation within said housing, about an axis concentric with the bur-receiving opening, means to supply motive air :to the interior of the housing to drive said turbine, conduit means within the housing separate from the air supply, said housing also having inlet means for water in communication wit-h said conduit means, said bur-receiving end of the housing being provided with a downwardly extending aperture to exhaust a portion of said motive air adjacent a bur-shaft driven by the turbine and substantially parallel thereto, and means to direct a stream of water from the conduit means into confluence with said exhausted air to form a downwardly projecting spray of air and water.

22. A generally cylindrical dental turbine housing having an opening at one end, an air-driven turbine within said housing in combination with bearing means mounting said turbine for rotation within the housing about an axis concentric with said opening, means to mount a bur on said turbine to project outwardly through said opening, means to supply motive air to the interior of the housing to drive the turbine, separate conduit means supported by the housing, said conduit means provided with inlet means for connection with a liquid supply means, said housing being provided with an aperture adjacent said opening to exhaust a portion of said air in a direction generally parallel with a bur shaft driven by the turbine,

said conduit means terminating in an outlet orifice positioned to direct said liquid angularly toward a bur shaft and into confluence with said exhausted air to atomize said liquid and form a spray to cool the working portion of the bur.

23. The invention as defined in claim 22, wherein said orifice of the conduit means is positioned in a plane normal to the axis of a bur shaft and spaced axially from said aperture for exhaust air.

References Cited by the Examiner UNITED STATES PATENTS 2,180,993 11/ 1939 Monnier. 2,705,838 4/1955 Blair 3Z28 2,824,370. 2/1958 Page 3227 2,866,267 12/1958 Fletcher et a1. 3228 0 RICHARD A. GAUDET, Primary Examiner.

JOHN R. KLINE, HAROLD B. WHITMORE, ROBERT E. MORGAN, Examiners. 

22. A GENERALLY CYLINDRICAL DENTAL TURBINE HOUSING HAVING AN OPENING AT ONE END, AN AIR-DRIVEN TURBINE WITHIN SAID HOUSING IN COMBINATION WITH BEARING MEAND MOUNTING SAID TURBINE FOR ROTATION WITHIN THE HOUSING ABOUT AN AXIS CONCENTRIC WITH SAID OPENING, MEANS TO MOUNT A BUR ON SAID TURBINE TO PROJECT OUTWARDLY THROUGH SAID OPENING, MEANS TO SUPPLY MOTIVE AIR TO THE INTERIOR OF THE HOUSING TO DRIVE THE TURBINE, SEPARATE CONDUIT MEANS SUPPORTED BY THE HOUSING, SAID CONDUIT MEANS PROVIDED WITH INLET MEANS FOR CONNECTION WITH A LIQUID SUPPLY MEANS, SAID HOUSING BEING PROVIDED WITH AN APERTURE ADJACENT SAID OPENING TO EXHAUST A PORTION OF SAID AIR IN A DIRECTION GENERALLY PARALLEL WITH A BUR SHAFT DRIVEN BY THE TURBINE, SAID CONDUIT MEANS TERMINATING IN AN OUTLET ORIFICE POSITIONED TO DIRECT SAID LIQUID ANGULARLY TOWARD A BUR SHAFT AND INTO CONFLUENCE WITH SAID EXHAUSTED AIR TO ATOMIZE SAID LIQUID AND FORM A SPRAY TO COOL THE WORKING PORTION OF THE BUR. 